1. Technical Field
The present invention relates generally to mobile communication systems and more particularly, to general packet radio services for delivering data over a circuit switch telephone network.
2. Related Art
The general packet radio service (GPRS) is a new non-voice value added service that allows information to be sent and received across a mobile telephone network. It supplements, or rides on top, of today's circuit switched data and short message service networks. The theoretical maximum speed of GPRS includes speeds of up to 171.2 kilobits per second (kbps). This maximum speed is achievable in GPRS systems using all eight timeslots at the same time in a time division multiple access (TDMA) context.
This speed is about three times as fast as data transmission speeds possible over today's fixed telecommunication networks and ten times as fast as current circuit switched data services on Global System for Mobile Communications (GSM) standard TDMA networks. Thus, GPRS systems are advantageous in that they require less system resources to transmit a fixed amount of data in comparison to using a traditional circuit switched approach. By allowing information to be transmitted more quickly, immediately, and efficiently, across the mobile network, GPRS may well be a relatively less costly mobile data service compared to SMS and circuit switch data.
GPRS also facilitates instant connections in which information can be sent or received immediately as the need arises, subject to radio coverage. No dial up modem connection is necessary. GPRS, similar to some broadband connections for personal computers, often is referred to as being “always connected.” Thus, another one of the advantages of GPRS is that data may be transmitted immediately, whenever the need arises. In contrast to circuit switched data in which a connection must be established to transmit a data packet or data file, GPRS operation is extremely efficient in those situations in which a small amount of data is to be sent.
As the emphasis of many designs today are to create wireless computer networks, and to connect data devices including personal computers to wireless transceivers and mobile terminals, such a system that provides instantaneous response is very important for time critical applications, and, more generally, for the implementation of wireless computer networks.
For example, a remote credit card authorization system implemented in a wireless network can be greatly improved if it is unnecessary for the customer to wait the amount of time that is required to establish a connection. Anyone that has waited at a cash register for credit authorization while a modem dials in and transmits account information can readily appreciate this advantage.
Additionally, GPRS facilitates the use of Internet applications not only from personal computers, but also from appliances and machines. It is anticipated that, in the future, appliances will be designed to be coupled to the Internet for control either onsite or remotely. While some people envision connecting these appliances to a network port by physical lines, it would clearly be advantageous to be able to connect such appliances to the Internet through a wireless link. GPRS will facilitate the creation of Internet controlled appliance networks through a wireless medium.
As suggested before, GPRS involves overlaying a packet based air interface on an existing circuit switched wireless network. For example, the circuit switched wireless network may comprise a GSM network. Accordingly, the user is given an option to utilize a packet based data service. In order to overlay a packet based air interface over a circuit switched network, the GPRS standard defines new infrastructure nodes to minimize the impact to existing networks in terms of hardware and software.
One advantage of GPRS is that packet switching that results from the infrastructure nodes allows the use of GPRS radio resources only when users actually are sending or receiving data. Unlike traditional circuit switched voice networks, a connection is not continuously reserved for a user for the intermittent transmission of data. This efficient use of scarce radio resources means that larger number of GPRS users can share the same bandwidth and be served from a single base station 216 or cell. The actual number of users, of course, that may use the system at one time depends on the amount of data being transferred.
Short message service (SMS) is a service that is provided in wireless telecommunication networks that enables short alphanumeric messages to be transmitted to and received from mobile telephones. Typically, a short messaging service center (SMSC) is formed and connected to a wireless network to enable mobile telephones to exchange short text messages with other networks. Typically, a short message service message is transmitted over a short message service channel (SMSCH). For example, in IS-136 networks, the SMSCH carries signaling information for set up and delivery of short alphanumeric messages from the cell site to the user terminal equipment. In IS-136, SMSCH is a logical subchannel of the SMS point-to-point messaging, paging and access response channel, which is a logical channel of the digital control channel. The digital control channel (DCCH) is a signaling and control channel that is employed in cellular networks, more particularly, in time division multiple access (TDMA) networks. The DCCH operates on a set of frequencies separate from those used to support the cellular conversations.
In current systems, either implemented or under design, a message center typically includes SMS processing logic as well as communication protocol logic for signaling system number seven (SS7) wireline circuit switched telephone networks. SS7 networks utilize a circuit switched plane for carrying voice and a tandem control plane to setup the circuit switching as a part of call setup. The message center typically transmit short message service messages over an SS7 network to a mobile switching center (MSC) that, in turn, transmits the SMS message to a serving GPRS support node (SGSN). The SGSN, in turn, forwards the SMS message to the wireless network, and more particular, to the base station for delivery to the destination mobile terminal.
It is desirable, however, to transition from an SS7-based network to a packet network, for example, one with an IP-based infrastructure. Economic and technical advantages, including speed of application development and lower costs due to economies of scale are being realized in the IP industry because of the huge success of the Internet. In order to ease the transition to new network architectures, while also supporting the functionality provided by SMS, there is a need to provide IP-based access to the message center. The current definition of the GPRS network architectures does not allow such IP-based access. Thus, as described before, SS7 telephone networks are used to transport SMS messages between the message center and the SGSN. It would be advantageous, however, if a message center could transmit SMS messages to an SGSN by way of a data packet network such as the Internet.